Conventional 55-gallon drums are used to store liquids and can be transported from one location to another by using a wooden pallet which sits beneath the 55-gallon drum. A forklift vehicle having forks is used to pick up and move the pallet and the drum thereon. In many applications today, a portable liquid container of the type disclosed in U.S. Pat. No. 4,746,034 to Ata et. al. is used for moving and storing up to 500 gallons of liquid without the need of a pallet. The Ata portable liquid container includes a four-sided shell enclosed by a bottom wall and a top wall. The bottom wall is formed by four triangular portions sloping downwardly to a delivery opening. The top wall has an opening which is normally covered by a lid. Two lifting channels and a valve disposed within the delivery opening are located on the underside of the bottom wall. The container is designed to be stackable upon a second like container. Four legs attached to the bottom wall support the container at a height sufficient to clear the valve and lifting channels. The lifting channels are designed to receive the forks of a forklift vehicle so that the forklift vehicle can pick up and transport the portable container. The container includes a sloped bottom wall which assures that all the liquid within the container will drain from the container through the delivery opening without having to tilt or otherwise manipulate the container.
A few problems occur with such a portable liquid container, however. First, since the lifting channels and valve are both located on the underside of the bottom wall, the valve is very susceptible to damage by the forks of the forklift vehicle. Second, since the lifting channels do not abut the surface upon which the four legs rest, it is difficult for the forklift vehicle operator to properly line up the forks to insert them in the lifting channels. This "alignment requirement" compounds the likelihood of valve damage and/or shell damage. Finally, with the valve located on the underside of the bottom wall, the access valve is difficult to access.
The assignee of the present invention has solved the above mentioned problems by making and selling (for more than one year before the filing date of this application) a portable bulk storage tank for containing liquids having a drain opening and valve disposed therein which are located on the side wall or shell portion of the container instead of the bottom wall portion. Additionally, the side wall portion of this container includes an indentation for enclosing the drain opening and valve to thereby protect the valve from the forks of a forklift. Also, the container comprises a substantially flat exterior bottom wall portion and a plurality of forklift tubes attached thereto. A flat exterior bottom wall portion is needed so that the tubes can support the container in an upright position. The forklift tubes also act as legs upon which the container rests on a surface. The forklift tubes are designed to receive the forks of a forklift from more than one direction.
With the indentation and valve located on the side wall portion and the need for a substantially fiat exterior bottom portion upon which the forklift tubes can rest, the liquid contained within the container cannot be completely drained from the valve without tipping the container. Since the valve is located above the exterior bottom wall portion, liquid lays on the surface of the exterior bottom wall portion especially in the areas or corners of the container between the walls of the indentation and the side wall portion. In other words, the liquid becomes trapped between the walls of the indentation and the side wall portion. Thus, a sloped false bottom is needed which directs the liquid away from these corners while also directing the liquid towards the drain opening.